Production method of hot-rolled extra-thick and ultra-wide bimetal composite plate

Abstract

According to the production method of the hot-rolled extra-thick and ultra-wide double-metal composite plate, S30403 is selected as a stainless steel layer, and the stainless steel layer comprises the following chemical components in percentage by mass: 0.02%-0.029% of C, 0.3%-0.5% of Si, 0.8%-1.0% of Mn, less than or equal to 0.04% of P, less than or equal to 0.005% of S, 18.0%-18.8% of Cr, 8.0%-8.2% of Ni and the balance of Fe and inevitable impurities; the base layer is made of Q355B low-alloy high-strength steel and comprises the following chemical components in percentage by mass: 0.06%-0.12% of C, 0.15%-0.3% of Si, 1.45%-1.6% of Mn, less than or equal to 0.02% of P, less than or equal to 0.005% of S, 0.02%-0.05% of Al, 0.008%-0.02% of Ti and the balance of Fe and inevitable impurities; the key process steps comprise assembling, heating, rolling, cooling and finishing, and industrial preparation of the high-performance bimetal composite plate with the width larger than 3.5 m, the total thickness not smaller than 100 mm, the base material larger than or equal to 90 mm and the stainless steel coating larger than or equal to 10 mm is achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of rolling compounding, and relates to a production method of hot-rolled super-thick and super-wide double-metal composite plate. BACKGROUND

[0002] The double-metal composite plate is widely applied to key fields such as pressure vessels, nuclear power, ocean engineering and military industry due to excellent mechanical properties, corrosion resistance and interface bonding. At present, the material is mainly produced by explosion compounding and rolling compounding, and the stainless steel composite plate is still mainly medium-thin specifications with a width of less than 3.5 m and a thickness of less than 60 mm.

[0003] With the development of modern industrial equipment towards large-scale, green and complex service environment, the market increasingly urgently needs wider and thicker high-quality stainless steel composite plates. However, the wide and thick stainless steel composite plate with a width of more than 3.5 m and a total thickness of more than 100 mm (of which the base material is greater than or equal to 90 mm, and the stainless steel cladding layer is greater than or equal to 10 mm) still faces major technical challenges in manufacturing process and quality control, and the related technology is still blank at home and abroad, which has significant market potential and development space. SUMMARY

[0004] The application relates to a production method of hot-rolled super-thick and super-wide double-metal composite plate, which aims to improve the plate shape and interface bonding quality of the composite plate by optimizing key processes such as group welding, heating system, rolling process and cooling control, and realizes the industrialized preparation of the high-performance double-metal composite plate with a width of more than 3.5 m and a total thickness of not less than 100 mm (of which the base material is greater than or equal to 90 mm, and the stainless steel cladding layer is greater than or equal to 10 mm).

[0005] The technical scheme of the application is as follows: The production method of the hot-rolled super-thick and super-wide double-metal composite plate is characterized in that the stainless steel layer of the composite plate is S30403, the chemical components of which are as follows in percentage by mass: C=0.02%-0.029%, Si=0.3%-0.5%, Mn=0.8%-1.0%, P<=0.04%, S<=0.005%, Cr=18.0%-18.8%, Ni=8.0%-8.2%, and the balance is Fe and inevitable impurities; the base layer is Q355B low-alloy high-strength steel, the chemical components of which are as follows in percentage by mass: C=0.06%-0.12%, Si=0.15%-0.3%, Mn=1.45%-1.6%, P<=0.02%, S<=0.005%, Al=0.02%-0.05%, Ti=0.008%-0.02%, and the balance is Fe and inevitable impurities; and the key process steps include: (1) Group blanking: adopt asymmetric AB type group blanking mode, A is Q355B base material, B is stainless steel cladding material. The total thickness of the blank meets the compression ratio of 3-5, and the surface treatment, assembly, welding blank packaging and vacuum extraction operations are carried out in turn.

[0006] (2) Heating: place the composite blank with the stainless steel surface facing down, and enter the furnace for heating within 72 hours after vacuum extraction; the heating temperature is 1180-1230℃, the total heating time is ≥blank thickness×1.0 min / mm, and the holding time is ≥blank thickness×0.2 min / mm.

[0007] (3) First stage rolling: the first pass reduction is ≤25mm, the reduction of each of the 2nd to 4th passes is ≥45mm, the finish rolling temperature is ≥1050℃, the cumulative reduction is 80%-100%, and the rolling speed is 1.5-2 m / s.

[0008] (4) Intermediate blank controlled cooling: after the first stage rolling, adopt laminar cooling, the cooling speed is 5-10℃ / s, and the final cooling surface temperature is 820-850℃.

[0009] (5) Second stage rolling: the starting rolling temperature is 800-820℃, the finish rolling temperature is 780-820℃, the rolling speed is 2.5-3.5 m / s, and the pass reduction is ≤10%.

[0010] (6) Controlled cooling: the starting cooling temperature is 750-780℃, the cooling speed is 5-12℃ / s, and the final cooling temperature is 650-690℃.

[0011] (7) Finishing: carry out splitting, straightening, sizing, surface treatment and packaging treatment on the composite plate.

[0012] Further, in step (1) blanking, in the asymmetric AB type blanking mode, automatic submerged arc welding is used for packaging and welding between the base layer and the cladding layer, the groove is double V type, the angle is 45°, the depth is 40mm, and the interlayer temperature is ≤200℃; the welding process is: first, use stainless steel electrode to lay the bottom, the weld depth is 20-25mm, weld 6-8 times, welding current is 350-400A, voltage is 28-32V, and welding speed is 20-24mm / min; then use carbon steel electrode to weld the transition layer, weld 3 times, welding current is 400-450A, voltage is 28-32V, and welding speed is 25-30mm / min; finally, use carbon steel electrode to cover the surface, the weld depth is 15-20mm, weld 8-11 times, welding current is 550-650A, voltage is 32-38V, and welding speed is 26-35mm / min.

[0013] Further, in step (2) heating: when heating, differential temperature control is adopted, so that the temperature of the lower stainless steel surface of the composite blank is higher than that of the upper surface, and the temperature difference is ≥5℃, so as to coordinate the synchronous deformation of the base layer and the cladding layer.

[0014] Further, in the first stage rolling of step (3) and the second stage rolling of step (5), differential speed control is adopted during rolling, so that the linear speed of the lower work roll is higher than the linear speed of the upper work roll by ≥5%, to coordinate the synchronous deformation of the base layer and the cladding layer.

[0015] Further, in the intermediate blank controlled cooling of step (4) and the controlled cooling of step (6), differential temperature control is adopted during cooling, and the cooling water amount ratio of the upper surface to the lower surface is controlled to be between 1 and 1.4, to realize uniform cooling of the base layer and the cladding layer, and to inhibit the interfacial internal stress.

[0016] Principle of the application: Asymmetric blank assembly design is adopted, and the internal structure and bonding quality are improved by increasing the compression ratio. In view of the fact that the ductility of stainless steel is lower than that of ordinary steel during hot rolling deformation and controlled cooling, in order to control the shape and ensure that the upper and lower layer metals extend uniformly during rolling, the stainless layer of the composite blank is placed downward in the present application, differential temperature heating is adopted in the heating furnace, so that the temperature of the lower surface is higher than that of the upper surface (temperature difference ≥5℃); differential speed rolling is adopted in rough rolling and finish rolling, so that the rolling speed of the lower roll is higher than that of the upper roll (speed difference ≥5%), to coordinate the uniform deformation of steel and stainless steel. In addition, considering the difference in thermal expansion coefficient between steel and stainless steel, the water ratio of the upper surface to the lower surface is reasonably set during rapid cooling, so that the shrinkage deformation of the two is matched, and the risk of cracks on the bonding surface caused by thermal stress is effectively reduced.

[0017] Advantages of the application: The hot-rolled wide and ultra-thick bimetallic composite plate produced by the method of the present application has the comprehensive advantages of good shape, high interface bonding rate, excellent shear strength and low residual stress, and successfully realizes the industrialized and stable production of such composite plates, which effectively promotes the application and popularization of the composite plates in the field of major equipment. DETAILED DESCRIPTION

[0018] The application will be further described below through examples. Example 1

[0019] A production method of a hot-rolled ultra-thick super-wide bimetallic composite plate is described by taking S30403 / Q355B hot-rolled wide and ultra-thick bimetallic composite plate with a blank thickness of 450mm, a total thickness of finished product of 110mm (base material 100mm+cladding layer 10mm) and a width of 3800mm.

[0020] The stainless steel layer of the clad plate is S30403, and the chemical components are as follows in percentage by mass: C=0.025%, Si=0.35%, Mn=0.85%, P=0.030%, S=0.002%, Cr=18.5%, Ni=8.12%, and the balance is Fe and inevitable impurities; the base layer is Q355B low-alloy high-strength steel, and the chemical components are as follows in percentage by mass: C=0.08%, Si=0.22%, Mn=1.51%, P=0.010%, S=0.001%, Al=0.035%, Ti=0.012%, and the balance is Fe and inevitable impurities; the key process steps include; (1) blanking: an asymmetric AB type blanking (A is Q355B base material, and B is S30403 stainless steel cladding material) is adopted, the ratio of the total thickness of the blank to the thickness of the finished product (compression ratio) is about 4.1, and the surface treatment, assembly, welding blank packaging and vacuumizing operations are sequentially performed.

[0021] (2) heating: the stainless steel is placed downward, and is heated in the furnace within 56 hours after vacuumizing. The heating temperature is 1205℃, the total time in the furnace is 560 min, and the holding time is 120 min. When the plate is taken out of the furnace, the upper surface temperature is 1190℃, and the lower surface temperature is 1200℃, the lower surface temperature is 10℃ higher than the upper surface, which meets the requirement of differential temperature heating.

[0022] (3) first stage rolling: a multi-pass large reduction process is adopted, the first pass reduction is 22mm, and the second to fourth pass reductions are 45mm, 46mm and 46mm respectively. The finish rolling temperature is 1070℃, and the cumulative reduction is about 92.6%. During the rolling process, the lower roller speed is always 5% to 10% higher than the upper roller speed, so as to coordinate the deformation and improve the plate shape.

[0023] (4) intermediate blank controlled cooling: after the first stage rolling, the laminar cooling is adopted, the cooling rate is controlled at 6℃ / s, and the final cooling surface temperature is 840℃.

[0024] (5) second stage rolling: the start rolling temperature is 820℃, the finish rolling temperature is 790℃, the rolling speed is 3 to 3.3m / s, and the process of the lower roller speed being 5% to 8% higher than the upper roller speed is continued, and the pass reduction rate is less than or equal to 6%.

[0025] (6) controlled cooling: the start cooling temperature is 760℃, the cooling rate is 7℃ / s, and the final cooling temperature is controlled at 660~670℃, so as to effectively inhibit the interfacial thermal stress.

[0026] (7) finishing: the clad plate is subjected to the processes of separating, straightening, sizing, surface treatment and packaging.

[0027] The rolling passes of Example 1 are shown in Table 1, and the properties of the produced steel are shown in Table 3.

[0028] Table 1 Rolling pass table of Example 1 . Example 2

[0029] A production method of hot-rolled super-thick ultra-wide double-metal clad plate is described by taking S30403 / Q355B hot-rolled wide super-thick double-metal clad plate with a billet thickness of 480 mm, a total finished product thickness of 140 mm (base material 120 mm + cladding layer 20 mm) and a width of 4000 mm as an example. The stainless steel layer of the clad plate is selected from S30403, and the chemical composition is as follows in terms of mass percentage: C = 0.026%, Si = 0.36%, Mn = 0.86%, P = 0.022%, S = 0.002%, Cr = 18.6%, Ni = 8.15%, and the balance is Fe and inevitable impurities; the base layer is Q355B low-alloy high-strength steel, and the composition is as follows: C = 0.08, Si = 0.23%, Mn = 1.52%, P = 0.011%, S = 0.0010%, Al = 0.038%, Ti = 0.012%, and the balance is Fe and inevitable impurities; the key process steps include: (1) Grouping: Asymmetric AB type grouping (A is Q355B base material and B is S30403 stainless steel cladding) is adopted, the compression ratio is controlled to be about 3.4, and the surface treatment, assembly, welding blank packaging and vacuum extraction operations are sequentially performed.

[0030] (2) Heating: The stainless steel is placed downward, and the heating is performed within 50 hours after vacuum extraction. The heating temperature is 1208℃, the total time in the furnace is 590 min, and the holding time is 140 min. The upper surface temperature is 1190℃ and the lower surface temperature is 1203℃ when the furnace is discharged, and the lower surface temperature is 13℃ higher than the upper surface, which meets the requirement of differential temperature heating.

[0031] (3) First stage rolling: Multi-pass large reduction process is adopted, the first pass reduction is 23 mm, and the second to fourth pass reductions are 46 mm, 47 mm and 45 mm respectively. The finish rolling temperature is 1080℃, and the cumulative reduction is about 92.5%. During the rolling process, the lower roller speed is always higher than the upper roller speed by 5%~9.5% to coordinate the deformation and improve the plate shape.

[0032] (4) Intermediate blank controlled cooling: The first stage rolling adopts laminar cooling, and the cooling rate is controlled at 6.5℃ / s, and the final cooling surface temperature is 838℃.

[0033] (5) Second stage rolling: The opening rolling temperature is 817℃, the finish rolling temperature is 788℃, the rolling speed is 3~3.3m / s, and the process of higher lower roller speed than upper roller speed by 5%~8% is continued, and the pass reduction rate is ≤6%.

[0034] (6) Controlled cooling: The opening cooling temperature is 764℃, the cooling rate is 6.5℃ / s, and the final cooling temperature is controlled at 662~675℃, which effectively suppresses the interfacial thermal stress.

[0035] (7) Finishing: separating, straightening, sizing, surface treatment and packing treatment of the clad plate.

[0036] The rolling passes of Example 2 are shown in Table 2; the properties of the produced steel are shown in Table 3.

[0037] Table 2 Rolling passes of Example 2 .

[0038] Table 3 Test results of properties of the produced steel of Example .

Claims

1. A method for producing a hot-rolled extra-thick and ultra-wide bimetallic composite plate, characterized in that: The stainless steel layer of the composite plate is made of S30403, with the following chemical composition by mass percentage: C=0.02%~0.029%, Si=0.3%~0.5%, Mn=0.8%~1.0%, P≤0.04%, S≤0.005%, Cr=18.0%~18.8%, Ni=8.0%~8.2%, with the balance being Fe and unavoidable impurities; the base layer is made of Q355B low-alloy high-strength steel, with the following chemical composition by mass percentage: C=0.06%~0.12%, Si=0.15%~0.3%, Mn=1.45%~1.6%, P≤0.02%, S≤0.005%, Al=0.02%~0.05%, Ti=0.008%~0.02%, with the balance being Fe and unavoidable impurities; Key process steps include: (1) Assembly: An asymmetric AB type assembly method is adopted, where A is Q355B base material and B is stainless steel cladding. The total thickness of the billet meets the compression ratio of 3~5. Surface treatment, assembly, billet welding and sealing and vacuuming operations are carried out in sequence. (2) Heating: Place the composite billet with the stainless steel side down, and heat it in the furnace within 72 hours after vacuuming; the heating temperature is 1180~1230℃, the total heating time is ≥ billet thickness × 1.0 min / mm, and the holding time is ≥ billet thickness × 0.2 min / mm; (3) First stage rolling: the first pass reduction is ≤25mm, the reduction of each pass in the second to fourth passes is ≥45mm, the final rolling temperature is ≥1050℃, the cumulative reduction rate is 80%~100%, and the rolling speed is 1.5~2 m / s; (4) Intermediate billet controlled cooling: after the first stage of rolling, laminar flow cooling is adopted, the cooling rate is 5-10℃ / s, and the final cooling surface temperature is 820-850℃; (5) Second stage rolling: the initial rolling temperature is 800-820℃, the final rolling temperature is 780-820℃, the rolling speed is 2.5-3.5 m / s, and the reduction rate per pass is ≤10%; (6) Cooling control: The starting cooling temperature is 750-780℃, the cooling rate is 5-12℃ / s, and the final cooling temperature is 650-690℃; (7) Finishing: The composite board is split, straightened, cut to length, surface treated and packaged.

2. The method for producing a hot-rolled extra-thick and ultra-wide bimetallic composite plate according to claim 1, characterized in that... Step (1) Assembly: In the asymmetric AB type assembly method, the base layer and the cladding layer are encapsulated and welded by automatic submerged arc welding. The bevel is double V-shaped, with an angle of 45° and a depth of 40mm. The interpass temperature is ≤200℃. The welding process is as follows: First, stainless steel welding rods are used for the root pass, with a weld depth of 20-25mm, 6-8 passes, a welding current of 350-400A, a voltage of 28-32V, and a welding speed of 20-24mm / min. Then, carbon steel welding rods are used for the transition layer welding, with 3 passes, a welding current of 400-450A, a voltage of 28-32V, and a welding speed of 25-30mm / min. Finally, carbon steel welding rods are used for the cover pass, with a weld depth of 15-20mm, 8-11 passes, a welding current of 550-650A, a voltage of 32-38V, and a welding speed of 26-35mm / min.

3. The method for producing a hot-rolled extra-thick and ultra-wide bimetallic composite plate according to claim 1, characterized in that... Step (2) Heating: Differential temperature control is used during heating to make the temperature of the stainless steel surface on the lower surface of the composite billet higher than that on the upper surface, with a temperature difference of ≥5℃, so as to coordinate the synchronous deformation of the base layer and the coating.

4. The method for producing a hot-rolled extra-thick and ultra-wide bimetallic composite plate according to claim 1, characterized in that: In the first stage of rolling in step (3) and the second stage of rolling in step (5), differential speed control is used during rolling to make the linear speed of the lower working roll ≥5% higher than that of the upper working roll, so as to coordinate the synchronous deformation of the base layer and the coating.

5. The method for producing a hot-rolled extra-thick and ultra-wide bimetallic composite plate according to claim 1, characterized in that: In step (4) intermediate billet controlled cooling and step (6) controlled cooling, differential temperature control is adopted during cooling, and the cooling water volume ratio of the upper and lower surfaces is controlled between 1 and 1.4 to achieve uniform cooling of the base layer and the cladding layer and suppress the interfacial stress.